Tag Archives: water in the garden

A last resort – getting in a digger

I have commented before that water in the garden can involve quite a bit of work, be it still water, treated water or running water. And water has had us busy this week.

The mill wheel bird bath can become a breeding ground for mosquitoes in summer

We have treated water – a swimming pool. Once that is up and running for the season, it doesn’t take much to keep it clean because we have a salt filter on a timer. We have still water – two pond features with goldfish and an historic mill wheel which serves as a bird bath. The problem with the mill wheel is that, without fish in it, the mosquitoes breed up within about three days so we have to drain it and replace the water often over summer. True, mosquitoes breed up anywhere there is still water, even in the bromeliads (and we have quite a few of those). But the mill wheel is close to our bedroom window so I blame that for the incursions of nasty, blood sucking critters in the night.

I cleaned out the excessive growth of the aquatic plants in the sunken garden this week. Goldfish stop this from being infested with mosquito larvae.

The goldfish ponds are relatively easy care. I go thorough a couple of times a year to scoop out the build-up of rotting detritus and to restrict the growth of the aquatic plants and we have to top them up with water in dry spells. The pond at the bottom of the sunken garden is too shallow so it evaporates quickly and we often get algae spreading that needs scooping out with a sieve but it is all pretty straightforward.

A last resort – Lloyd on the digger. You can see the mat of grass that had established on the choking silt.

Running water – the stream in the park – is nowhere near as simple to maintain. This week, we admitted defeat and hired a digger. We haven’t put a digger through the stream for about 25 years and it is an absolute last resort because it destroys the entire eco-system. Generally, we can get away with going through with a long-handled rake and drainage fork every couple of years to haul out the excessive growth of choking weeds – back breaking work but kinder to the environment. This time it was beyond that and the issue was the excessive build up of silt. We were at the point where the stream was turning into a swamp with little water movement.

There were four reasons for this state of affairs and only one of those was caused by our management. The water that flows looks clean enough to the naked eye. As Mark observed, it is a good example of how a visual assessment is not an accurate guide to water quality. Because it flows through farmland upstream, the silt loading is high. It runs dirty every time it rains and and over the years, the silt dumped on our stretch had built up. It also carries a very high nutrient loading from farm runoff and that means we are battling water weeds all the time. Then when the culvert at the corner was replaced last summer, it involved earth works on our place and the soil was not compacted so there was a major collapse during a flood. That reduced the water flow through the park by at least 50% with the water going over the weir and down the flood channel instead. Digging out that silt bank blocking the stream was too big a job to do by hand.

Neither Mark nor I were game to try driving the digger but fortunately Lloyd is not afraid of machinery though cautious by nature.

The fourth problem was of our making. When we decided to manage the park as a meadow and reduce mowing to just twice a year, we also stopped strimming the banks of the stream. With the build-up of silt and the greatly reduced water flow, the grass had invaded the river and formed a mat that was too heavy to dig out by hand. Hence the digger. We can’t get a big digger in because of access restrictions and the placement of many trees and shrubs so Lloyd spent two days quietly and cautiously working his way round the areas that could be accessed safely from the cab of the little digger. Its reach is not long enough to scoop the two ponds we have so they remain an unresolved issue at this stage. We are thinking we want to create a channel for the water and turn the ponds into bog gardens but the details of how we manage that transition are not quite clear yet. Natural ponds are even harder to maintain than the stream and we think it is time to draw the line beneath having those.

Mark will probably plant trees to shade more of the stream. When water is shaded, it stops the rampant growth of choking water weeds and it is much easier to stand on the bank and rake out what is there.

This was just a small eel that appeared a little disoriented at finding itself on dry land. I helped it find the water again.

I have a vested interest in this. I have found that it is easier to weed the stream by dropping the level (which we can do with the weir and the flood channel) and getting in the water to clear it. It is a very muddy procedure but easier on my back than doing it from the bank. I started doing this last week before we decided to get the digger. I cleared one stretch of several metres but I can never get in that water again. The next day, I was back again, this time raking from the bank just down from that area I had cleared. And lo, there was a very large eel undulating through the shallow water. I am always aware of my tendency to hyperbole so I didn’t want to exaggerate its size but Lloyd spotted it sunning itself the next day and estimated it to be about 80cm or more in length with a girth behind its head of close to 50cm in circumference. I knew we had eels. I had to head one in the right direction to get back in the stream and I have seen many small ones. But that is too large an eel for me and there may well be more than one of them that size. I am scared of eels.

The aim is to manage the stream without needing to resort to a digger again – at least in our lifetime.

The battle with the water weeds

We have dropped the water level for me to hand scoop the stream

We have dropped the water level for me to hand scoop the stream

I have been getting really down and dirty this week, hand pulling the weed from our main stream. As this involves wading in mud up to my knees, I emerge looking decidedly worse for the wear and no, you are not going to see a photo of me in this state.

Our main issues are with dreaded oxygen weed, Cape Pond weed and blanket weed. If we didn’t stay on top of them, the entire water surface would disappear below vegetation, which rather defeats the purpose of having a stream in the garden. I asked Mark if he thought our problems were related to farm run-off and excessive nitrogen but he is of the opinion that it has more to do with slow water flow rates, though he felt the build up of mud and silt in our streambed would be extremely fertile. When we get sudden bright green algal bloom, it is an indication of nitrogen being applied on farms upstream.

The worst offenders: Cape pond weed and oxygen weed

The worst offenders: Cape pond weed and oxygen weed

There is something very appealing about a natural stream but they are not without their problems. Offhand, I thought of three gardening colleagues with natural streams. One has problems with flooding in torrential rain. The water cannot get away fast enough so it builds up on his property. One has no problem at all with flooding because their stream is in a deep ravine, maybe 20 metres below the level of their land, but this means it isn’t really a significant garden feature. The third has a picturesque mountain brook to die for, bar two factors. Their land has sufficient natural fall to clear flood waters quickly but the bubbling brook can turn into a torrent that scours everything alongside. This means that they can’t have streamside plantings of any quality. They tried two or three times before giving up, having seen the plants ripped out and carried away. Their second issue is that the water is of high purity so a number of neighbours have water rights granted. Each neighbour has installed their own alkathene pipe at the top of our friends’ garden where the stream enters, running the pipes along the streambed until they exit at their adjoining properties down the bottom. There must be at least five alkathene pipes, both black and garish white, visible in that stream. It is not a good look.

So be careful what you wish for. None of these people, however, have to do what we do and clear the waterway of vegetation every year or two. We eliminated problems with flooding and scouring but our water flow is not sufficient to stop the growth of water weed. Our wonderfully natural looking stream is actually the result of outside expertise and in-house experience coming up with a low tech solution. We control the water where it enters our property by means of a simple weir. In normal conditions, this allows the water to flow equally down two streambeds. One meanders pleasantly through our park while the other is a deeper flood channel girded by stop banks. The two stream beds join up again on the other side of our property so the flow downstream is completely unaffected. When heavy rains cause flooding, a mechanism is triggered which directs all the water down the flood channel. By these simple means, we eliminated flooding, boggy patches and scouring from the park though we do have to manually reset the weir in order to get the water flowing again.

The pond weed is the direct result of having a relatively low flow through the park area, though our stream is such that it never dries up. Oxygen weed is a curse. We had a bad infestation which Mark finally eliminated entirely for some years. He blames the reinfestation on people emptying unwanted goldfish bowls into the stream at the corner by the road. Do not ever do this. The goldfish are most likely to die but the oxygen weed is an invasive menace in slow moving water.

Our other great burden comes from a former neighbour who, as far as Mark is concerned, should be lined up and shot for liberating such an invasive weed. African Cape Pondweed, also known as water hawthorn, (botanically Aponogeton distachyum) is undeniably pretty, with a very long flowering season. Presumably this is why the former neighbour planted it on the margins of his ponds. Because he had no control over the water flow, the inevitable floods scoured it all out of his place but it found a lovely home in our slow moving sections. I don’t know how many hundreds of hours we have spent rooting it out. It is quite good friends with the oxygen weed because it can grow through it and spread its lily pad-like leaves. Between them they have the potential to turn our stream to bog. Native weeds are nowhere near as aggressive.

It is only yours truly who has shed most clothes to get in and hand pull the water weeds this year. Generally this is done by the two men in my gardening life (Mark and Lloyd) who take it in turns to wield the long handled rake and manually haul it all out on to the bank. It is a slow process and pretty hard on their backs. I thought it would be faster and easier to do it by getting in and so it is proving to be. The water is pleasantly warm, the mud even more so on sunny days. I just have to time my mud wrestling because I can’t exactly stop for lunch or a cuppa. Wisecracks about eels are not welcome.

Lloyd at least stays cleaner on the end of the rake but it is harder on the back

Lloyd at least stays cleaner on the end of the rake but it is harder on the back

First published in the Waikato Times and reproduced here with their permission.

The pitfalls and perils of garden water features

It may be a natural stream in our park but it is hardly an easy care water feature

It may be a natural stream in our park but it is hardly an easy care water feature

Water is an important inclusion in any garden, or so the common wisdom says. We laughed when Joe Swift on BBC Gardener’s World commented that he hated water features because they were rarely maintained. Water is difficult to manage well.

A natural stream might seem the best option for the lucky ones and on a fine day, the mountain brook that bounces its way through Ngamamaku Garden is indeed a source of envy for many of us. The trouble is that with our torrential downpours, natural streams can quickly become raging torrents which take out all your plantings. Tony has long since given up using treasures in his stream-side plantings. They disappear in the flood torrents. We have the upper reaches of the Waiau Stream running through our park and again, it is charming and a great asset. Because we control the flood waters by some simple but time honoured techniques (a weir and a flood channel), we don’t get the scouring but it takes constant management to prevent it all silting up and regular, heavy work to keep the water weeds under control – particularly oxygen weed and Cape Pond Weed.

Ponds – are ponds easier? Possibly the larger your pond, the more self maintaining it becomes though you generally need fish (commonly goldfish) to keep the mosquito larvae at bay. By definition here, a lake is sufficiently large to allow water skiing, or at least canoeing. If it is not of that dimension, it is a pond. Maybe a large pond, but a pond. By the time your pond has shrunk below about a metre square or round, it can’t really be called a pond any longer. A puddle, perhaps, or a basin? If you have a natural pond fed by a spring, it may stay fresher and relatively stable through the seasons. Home made ponds can be difficult. Firstly they are prone to developing leaks and that is a terminal condition unless you remedy the problem – which is never easy to do. Shallow ponds are problematic because the water heats up and that encourages algae growth. If it is too deep (somewhere about 40cm), you have to fence it. Basically a pond, by definition, is a static body of water which will therefore go stagnant. And homemade ponds are often lined in polythene which is really hard to manage so it is not visible in any way at any time – folds of polythene just look really tacky.

The formal pond that depends on pristine water quality shrieks out money. I have seen a couple and essentially they are the same as running a swimming pool – dependent on a full filtration system and frequent vacuuming. I have a few ethical issues with their sustainability and personally that swimming pool look does not strike me as aesthetically pleasing. It is all a bit too Beverley Hills. If you are going to have something that looks akin to a swimming pool, it may as well combine function with form and be a swimming pool. I also particularly dislike the hum of the pump as a background sound in the garden. To do it properly, you need a silent pump. The same goes for any water feature which relies on moving water to a part of your property where it does not naturally occur. Circulating the water does at least solve the problem of it becoming stagnant but it is a fraught activity, more often prone to lapses in taste and poor management. Fountains? A matter of taste. Repro classical fountains don’t do it for me. I have seen enough of the real thing in European gardens, which is where they belong – usually in the gardens of royalty or at least wealthy nobility. The increasing democratisation of the classic fountain hasn’t done much for its aesthetics. They are just a little “Look at me! Look at me!” in the average New Zealand garden. Leave them for Versailles.

The overseas fashion for rills or narrow canals has been slower to catch on here. I think the origins for these lie in Islamic gardens – the requirement to wash before frequent prayers. In recent years, English garden designers rediscovered them and you see the ribbon of lawn bisected with the water channel, often only 20cm wide. Hmmm. The words drainage channel and lacking in purpose spring to mind so we will say no more on the topic.

Mark has a mantra that design features in a garden need a logic to them, they need to make sense in the context. So creating a naturalistic waterfall cascading down from a dry hillside is a contradiction in itself. The fountain in the formal garden is not pretending to be natural – it is all about the imposition of human will and design on nature. The waterfall is trying to simulate a natural event so it needs to be as close to seamless as possible, not, as more often happens, a feature plonked in to “add interest” with little regard to logical context. Being able to hear the pump thrumming away as it circulates the water makes it even worse.

None of the above is to deny that it is possible to do water features well and when they are done well, they are a welcome addition to the garden, whether it be a reflecting pool, the sound of a babbling brook or cascading water, a formal design feature or a modest goldfish pond. The mistake is to think that they are mandatory and once in place, that they need no attention. And I own up to the fact that we have a formal goldfish pond which is severely afflicted by algal bloom at the moment.

The simplest type of water feature - in this case a stone millwheel with a bung in the base so it can be drained and refilled easily

The simplest type of water feature - in this case a stone millwheel with a bung in the base so it can be drained and refilled easily

A word on safety: we have all had it drummed in to us that children can drown in as little as 7.5cm of water, which means they can drown in a puddle, really. We were told by an inspector some years ago that the reason so many little ones drown in swimming pools is because they are attracted by the blue colour that is the norm and that once in, they instinctively try to reach the bottom to stand up. Vertical sides also make it near impossible to get out. These aspects do not generally apply to garden water features but if the safety aspects worry you, it may be better to dispense with the feature altogether rather than try and net it over.

If you absolutely must have water and your garden is small, a large container with some sort of plug or bung system to enable drainage is probably the most easy-care solution. You can then replace the water when the mosquito larvae start swimming around or it all turns green and yukky. If you plan anything more ambitious, think carefully before you start and be prepared to maintain it.

How ironical is it that one of the very best examples of gardening we have seen internationally is Beth Chatto’s dry garden in the UK? The dry, gravel garden at Hyde Hall nearby is also shaping up brilliantly. Mind you, both are in very arid, stony areas. Similar plants would rot out in our higher rainfall and humid conditions. But generally it is better to garden with the conditions and not to feel that one simply must introduce a water feature to counteract the dry areas.